Unit Name: Grumbler Group
Unit Type: Lithostratigraphic
Rank: Group
Status: Formal
Usage: Currently in use
Age Interval: Frasnian (385.3 - 374.5 ma)
Age Justification: The Grumbler Group contains a well-developed coral-brachiopod fauna.
Province/Territory: Alberta; British Columbia; Northwest Territories

Originator: Crickmay, 1953, 1957; given group status by Belyea and McLaren, 1962.

Type Locality:
First described by Crickmay (1953) as a series of outcrops on the upper course of Hay River; in 1957 emended, at the type locality, to include the section from 103.8 km (64.5 mi) by road to 57.1 km (35.5 mi) by road, ending at a point 1.6 km (1 mi) above Alexandra Falls.

Distribution:
Southern District of Mackenzie, northeastern British Columbia and northwestern Alberta west of the 117th Meridian and north of the 57th parallel. It is truncated to the northeast by pre-Cretaceous erosion and passes westward to approximately the 122nd Meridian into shales of the Besa River and Fort Simpson formations in northeastern British Columbia and the adjacent District of Mackenzie respectively. It ranges in thickness from approximately 91 m (300 ft) to 122 m (400 ft) in northern Alberta and the southern District of Mackenzie but increases in thickness westward to approximately 152 m (500 ft) west of 120° and to 183 m (600 ft) before passing completely into the shale section.

Lithology:
Generalized lithologies for the 4 component formations are listed in ascending order: 1) bioclastic, reefoid and biostromal limestone (Twin Falls Formation); 2) grey calcareous siltstone and silty and sandy mudstones with fine grained silly limestones (Tathlina Formation); 3) greenish-grey and maroon calcareous mudstone and shales and argillaceous silty dolomites (Redknife Formation); and 4) yellowish-grey and olive-grey quartzose silty dolomitic limestones with argillaceous partings (Kakisa Formation).

Relationship:
The Grumbler Group conformably overlies the Hay River Formation and is overlain by the Trout River Formation. The upper part, including the Redknife and Kakisa equates to the Winterburn Group of central Alberta; the Grotto Arcs and Ronde members of the Southesk Formation of the Alberta Rocky Mountains and the upper part of the Duperow and Birdbear of Saskatchewan and northern Montana. The Tathlina Formation and Twin Falls Formation and the Alexandra and Escarpment members corre-late with the Grosmont Formation, the upper part of the Woodbend Group of central Alberta, the Peechee Member of the Southesk Formation of the Alberta Rocky Mountains and the upper part of the Duperow of Saskatchewan.

History:
As the type section is incomplete, Crickmay described a supplementary section on Trout River from 4.8 km (3 mi) above the Third Falls to 12.5 km (8 mi) below them. Later mapping by the Geological Survey of Canada showed that "the lowest outcrop on Trout River lies some 106.7 m (350 ft) stratigraphically higher than the highest outcrop on Hay River." Hence, the Grumbler Formation was given group status by Belyea and McLaren (1962) to include "all strata of early upper Devonian (Frasnian) age lying above the Hay River Formation. The Group includes in ascending order the Twin Falls, Tathlina, Redknife and Kakisa formations (Crickmay's Alexandra Formation is a local facies at the base of the Twin Falls).

Other Citations:
Belyea, 1964; Cameron, 1922; Harding, 1957; Law, 1955a.

References:
Belyea, H.R. and McLaren, D.J., 1962. Upper Devonian formations, southern part of Northwest Territories, northeastern British Columbia and northwestern Alberta; Geological Survey of Canada, Paper 61-29, 74 p.
Belyea, H.R., 1964. Chapter 6 - Upper Devonian, Part II - Woodbend, Winterburn and Wabamun Groups, in, Geological History of Western Canada, McCrossan, R.G. and Glaister, R.P. (eds.); The Alberta Society of Petroleum Geologists, Canadian Sedimentary Basins Symposium, pp. 66-88.
Cameron, A.E., 1922. Hay and Buffalo rivers, Great Slave Lake and adjacent country, Northwest Territories; Geological Survey of Canada, Summary Report 1921, Part B, pp. 1-44, contains Map 1585, "Mackenzie River Basin (74, 75, 83, 84,85, 86, 94, 95, 96, 104 P, 105 A P, 106).
Crickmay, C.H., 1953. New Spiriferidae from the Devonian of western Canada. Pub. by author, Imperial Oil Limited, Calgary, 11p.
Crickmay, C.H., 1957. Elucidation of some Western Canada Devonian Formations; published by the author, Imperial Oil Limited, Calgary, Alberta, 14 p.
Harding, S.R.L., 1957. Biohermal reef outcrop in lower part of Grumbler Formation; Canadian Society of Petroleum Geologists, Journal of the Alberta Society of Petroleum Geologists, vol. 5, no. 5 (May), pp. 111-113.
Law, James, 1955a. Geology of northwestern Alberta and adjacent areas; American Association of Petroleum Geologists (AAPG), Bulletin of the AAPG, vol. 39, no. 10 (October), pp. 1927-1975.

Source: CSPG Lexicon of Canadian Stratigraphy, Volume 2, Yukon Territory and District of Mackenzie; L.V. Hills, E.V. Sangster and L.B. Suneby (editor)
Contributor: D.W. Morrow; P.A. Monahan; H.R. Balkwill
Entry Reviewed: Yes
Name Set: Lithostratigraphic Lexicon
LastChange: 23 Nov 2010